The present invention relates to a large power magnetron for use in industrial applications and more particularly, to a structure for retaining a radio frequency (r.f.) gasket on such a magnetron.
Large power magnetrons, such as the RCA 8684, are capable of continuously generating r.f. power of 30 kilowatts at very high efficiency. However, care must be exercised by the tube operator to ensure that the r.f. seals between the magnetron and the external output circuitry, which includes a waveguide transition member having an insulating sleeve therein that accommodates an output dome insulator of the magnetron, are adequate to limit the r.f. radiation to safe and acceptable values. To this end, a conductive r.f. gasket is disposed between a conductive output support ring of the magnetron and the waveguide transition member which is secured to a waveguide. In some applications, the magnetron is inserted into the transition member in an inverted orientation so that the r.f. gasket is directed downwardly. In the prior art, it is known to use small strips of aluminum foil tape to retain the r.f. gasket in electrical contact with the output support ring of the magnetron. However, there is evidence that occasionally the tape fails to retain the r.f. gasket in place, especially when the magnetron is inverted for installation. In such cases, the r.f. gasket becomes lodged between the output dome insulator of the magnetron and the insulating sleeve of the waveguide transition member. As a result, arcing occurs and damages the output dome insulator of the magnetron causing premature failure of the magnetron.